A drive motor controller of an electric vehicle mainly includes a power supply module, a minimum module, a rotary transformer circuit, a drive module, a power module, an IPM (intelligent power module), a sampling module and an input/output switch module etc. The power supply module can provide voltage to each module of the controller for working normally. For example, the minimum module is provided with 3.3V, 1.9V or 5V voltage to work normally, the rotary transformer circuit is provided with +5V or ±15V voltage to work normally, the drive modules is provided with +15V, −8V or +5V voltage to work normally, the power module is provided with 460V high-voltage to work normally, the intelligent power module is provided with +12V or +5V voltage to work normally, the sampling module is provided with +5V, +3.3V, +3.3VA, +5V or +12V voltage to work normally, the input/output switch module is provided with +5V, +3.3V or +12V voltage to work normally. The minimum module mainly includes a DSP (Digital Signal Processor), a flash memory, a watchdog, an EEPROM (Electrically Erasable Programmable Read-Only Memory), a crystal oscillator, a burning mouth, etc. The rotary transformer circuit is configured to sample a current position of a motor rotor in real-time. The PWM (Pulse Width Modulation) wave output from the DSP is transferred to the drive chip after level conversion, filtering and phase inversion, so as to drive the power module. The power module (i.e., IGBT (Insulated Gate Bipolar Transistor) module) is a power component of the controller, and the motor is controlled to work or to stop working by controlling IGBTs in the power module to turn on or off. The IPM is used to realize an over-temperature protection and an over-current protection of the IGBT module, and can latch a fault signal and send the fault signal to the DSP. The sampling module is mainly used to realize a throttle sampling, a brake sampling, a motor temperature sampling, a radiator temperature sampling, a high voltage sampling, a battery voltage sampling, a three-phase current sampling, a humidity sampling and a body inclination angle sampling, etc. The input/output switch module includes a handbrake sampling, a footbrake sampling, a high voltage interlock sampling, a power-off protection and a collision signal sampling, etc.
In the related art, the drive motor controller generally works as follows: when a crash signal of the DSP is detected, the controller directly turns off all the PWM waves of the drive signal, so as to turn off all the IGBTs in the power module, regardless of a motor speed (a driving speed of a vehicle). In this case, a counter electromotive force of the motor is higher than a voltage across a battery, and thus the energy of the motor at a high rotating speed (represented as the counter electromotive force of the motor) can be charged to the battery instantaneously via a uncontrollable rectifier of the drive motor controller. The uncontrollable rectifier instantaneously charges the battery and a bus capacitor, and due to a large current of the uncontrollable rectifier, the battery and the bus capacitor may be damaged. Moreover, since the counter electromotive force of the motor is too large, the drive components and the power components of the drive motor controller may be damaged. Furthermore, since the motor has a great feedback torque, an uncontrollable and large braking force is generated, which results in that the motor shakes intensely and makes the vehicle in an uncontrollable state.
The existing technology has following disadvantages. When the DSP is in a crash state, the PWM wave of the drive signal sent out from the drive motor controller is in an unknown state, and if the vehicle is now in a high-speed driving state, the vehicle may have an intense back and forth shaking and get out of control, and even the drive components or the power components may be damaged.